Common REXT/MV-HEVC/SHVC (47) Summary (1)
The documents in this section were discussed in joint AHG/BoG sessions with JCT-VC experts. For documentation about these discussions and conclusions, refer to the report JCTVC-P1000 and BoG report JCT3V-G0233. Decisions and adoptions for HLS of joint interest for MV-HEVC and SHVC were made in a joint meeting of JCT-VC and JCT-3V on Sunday 12th Jan. 2-3 PM. Adoptions are also documented in section 14 of this report.
In a follow-up meeting Tue 11-13, GS reports about further suggestions of the BoG: Aspects of DPB and sub-layer DPB sharing may have impact on multi-view. This was further discussed and no concerns were raised from the JCT-3V side about the flexible approach (allowing to define either separate or sub-layer shared DPB dependent on profile/level) by JCT-VC.
14.1.1.1.1.1.1.1.92JCT3V-G0233 Joint BoG report on High Level Syntax [J. Boyce ]
Presented and further discussed in joint JCT-VC/3V plenary Sunday 01-12 am (JRO & GJS).
The suggested plan for publication for ISO/IEC was described as follows:
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Edited DAM or FDAM considered issued in April for RExt and MV-HEVC, but not balloted to enable preparation of new FDIS.
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Edited DAM or FDAM considered issued in July for SHVC, but not balloted.
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FDIS of new edition issued in July with all three amendments integrated, and balloted.
(Consent in July of full text new edition.)
Decision: The BoG recommended, and the JCT-VC/3V, endorsed, the following actions:
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Remove profile_ref_minus1 from the VPS extension, from JCTVC-P0048/JCT3V-G0040
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Move video signal information syntax structure earlier in the VPS VUI, from JCTVC-P0076/JCT3V-G0090
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Not signal the sps_max_num_reorder_pics[], sps_max_latency_increase_plus1[], and sps_max_dec_pic_buffering_minus1[] syntax elements in the SPS when nuh_layer_id > 0, from JCTVC-P0155/JCT3V-G0144.
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Add PPS extension type flags for conditional presence of syntax extensions per extension type, aligned with the SPS extension type flags, from JCTVC-P0166. Further align the SPS extension type flags syntax between RExt and MV-HEVC/SHVC.
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Modification of derivation of variable NumActiveRefLayerPics from JCTVC-P0079/JCT3V-G0092.
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Require that end of bitstream NAL unit shall have nuh_layer_id equal to 0, from JCTVC-P0130/JCT3V-G0131. Decoders shall allow an end of bitstream NAL unit with nuh_layer_id > 0 to be present, and shall ignore the NAL unit.
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Add constraint restricting pictures marked as discardable from being present in the temporal or inter-layer RPS, from JCTVC-P0130/JCT3V-G0131.
The BoG recommended the following activities take place:
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To further discuss JCTVC-P0110/JCT3V-G0116 to select between two options to enable no default output layer sets (See notes for P0110 in JCT-VC report, which recorded the decision in the follow-up joint meeting Tue 11).
Further BoG activity was conducted afterwards. The final recommendations, which were endorsed by JCT-VC and JCT-3V, are reflected below (as far as any of the following aspects would be conflicting with the statements above, the following shall be considered to reflect the final outcome).
JCTVC-P0187/JCT3V-G0162 On inference of NoOutputOfPriorPicsFlag
This contribution discusses the inference of NoOutputOfPriorPicsFlag and proposes to take into account colour format and bit depth for the inference in addition to spatial resolution. Decision (BF & corrigendum): Adopt
JCTVC-P0043/JCT3V-G0032 Access unit boundary detection
Decision (BF/Corrigendum): Clarify the text such decoders conforming to profiles specified in Annex A do not use NAL units with nuh_layer_id > 0 for AU boundary detection and that non-nested HRD parameters describe Annex C operation for this type of AU boundary detection
JCTVC-P0041/JCT3V-G0031 On picture order count
It was remarked that we should require each non-IRAP picture that has discardable_flag equal to 1 to have NUT value indicating that it is a sub-layer non-reference picture. This was agreed. Decision: Adopt (with constraint for discardable_flag as described above).
JCTVC-P0056/JCT3V-G0042 Layer-tree POC
Proposal 1: If the POC reset approach is adopted as the basis for multi-layer POC derivation, it is proposed to derive the POC anchor picture from the previous TID0 picture (that is not a RASL picture, a RADL picture or a sub-layer non-reference picture and not with discardable_flag equal to 1) of the current layer or any of its reference layer. Decision: Adopt Proposal 1 (with the suggested modifications – with text provided as P0297).
JCTVC-P0110/JCT3V-G0116 On default output layer sets
Decision: Three-state approach (text in P0295, decoder shall allow 3 to be present and shall treat 3 the same as the value 2).
JCTVC-P0157 On Indications for Inter-layer Prediction
Decision (SW): Make this change to the RA config file and provide the addition nesting config file in the RS package (assuming it causes no unforeseen difficulties).
JCTVC-P0138/JCT3V-G0138 HRD parameters for bitstreams excluding CL-RAS pictures
Decision: Adopt (as revised in updated contribution, with the specification of a flag in the BP SEI message).
JCTVC-P0156/JCT3V-G0145 On DPB Parameters in VPS
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Proposal 1 of this document proposes to signal, in the VPS extension, the DPB parameters for an output layer set for sub-DPBs only up to the maximum temporal sub-layers in the corresponding layer set.
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Proposal 2a: The derivation of NumSubDpbs[i] is modified to use correct index into the NumLayersInIdList list.
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Proposal 2b: Also inference for output_layer_set_idx_minus1[ i ] for default output layer sets is defined.
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Proposal 3: The output_layer_flag[i][j] is signalled for j equal to 0 to NumLayersInIdList[ lsIdx ] inclusive. It was remarked that we might be able to just assume that the top layer is always output; however, this was not entirely clear (e.g., for auxiliary picture layers), so the safe thing to do may be to also send the flag for this layer.
Decision (cleanup): Adopt (all four aspects).
JCTVC-P0192/JCT3V-G0161 On decoded picture buffer management
Decision (Ed.): Editorial aspects delegated to the editors for consideration
Establish sub-DPBs based on the representation format indicated at the VPS level. This approach was preferred. It was suggested that the expressed shared capacity limit would need to be less than or equal to the sum of the individual capacity limits. Decision: Adopt as modified. Further study is encouraged on profile/level constraint selections.
JCTVC-P0182/JCT3V-G0160 On Sub-bitstream extraction and re-writing process
"base_layer_parameter_set_compatibility_flag" was suggested as an alternative flag name. Decision: Define the flag (in VPS VUI) with the proposed semantics, without specifying an associated extraction process. Editors to select the position in the VPS VUI.
JCTVC-P0290 Joint BoG report on High Level Syntax [J. Boyce]
Decision: The BoG recommended, and the JCT-VC/3V, endorsed, the following actions:
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Remove profile_ref_minus1 from the VPS extension, from JCTVC-P0048/JCT3V-G0040
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Move video signal information syntax structure earlier in the VPS VUI, from JCTVC-P0076/JCT3V-G0090
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Not signal the sps_max_num_reorder_pics[], sps_max_latency_increase_plus1[], and sps_max_dec_pic_buffering_minus1[] syntax elements in the SPS when nuh_layer_id > 0, from JCTVC-P0155/JCT3V-G0144.
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Add PPS extension type flags for conditional presence of syntax extensions per extension type, aligned with the SPS extension type flags, from JCTVC-P0166. Further align the SPS extension type flags syntax between RExt and MV-HEVC/SHVC.
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Modification of derivation of variable NumActiveRefLayerPics (confirmed 01-16)., from JCTVC-P0079/JCT3V-G0092.
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Require that end of bitstream NAL unit shall have nuh_layer_id equal to 0, from JCTVC-P0130/JCT3V-G0131. Decoders shall allow an end of bitstream NAL unit with nuh_layer_id > 0 to be present, and shall ignore the NAL unit
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Add constraint restricting pictures marked as discardable from being present in the temporal or inter-layer RPS, from JCTVC-P0130/JCT3V-G0131
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Add a flag in VUI to indicate that all IRAP pictures are IDRs and that all layer pictures in an AU are IDR aligned, from JCTVC-P0068/JCT3V-G0085 proposal 1. Decision: Adopted.
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Several minor modifications to the VPS syntax, consistent with eliminating the previous intention to avoid ue(v) parsing in the VPS, as represented in JCTVC-P0306/JCT3V-G0240. Decision: Agreed.
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Several additional questions were suggested to be discussed in the track:
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Is the VPS VUI extension offset necessary? Should there be a mechanism for additional extension of the VPS extension before the VPS VUI? The syntax provided by Y.-K. Wang in P0307/JCT3V-G0241. Decision: Adopt modification in P0307/JCT3V-G0241.
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Is the VPS extension offset necessary in the VPS? If so, how to address the start code emulation issue raised in JCTVC-P0125? Decision: Keep it as a reserved FFFF value.
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Add alpha channel information SEI message, from JCTVC-P0123. Decision: Adopt. Constrain the bit depth indicated to be equal to the coded bit depth of the aux picture.
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Add sub-bitstream property SEI message, from JCTVC-P0204/JCT3V-G00165. Decision: Adopt.
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Change alt output layer flag to be signalled within the loop of output layer sets, from JCTVC-P0300//JCT3V-G0238-v2. Decision: Adopt.
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Further discussion of JCTVC-P0133/JCT3V-G0134, on recovery point and region refresh information SEI messages. Discussed 01-16 (GJS). Decision: Adopt change to recover point semantics only (-v3). Further study was requested regarding region refresh information SEI message.
Decision (Ed.): The BoG recommended, and the JCT-VC/3V endorsed, the following suggestions to the editors:
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Improve or add definitions in the MV-HEVC and SHVC specifications for layer sets, target output layers, output layer sets, and consider adding explanatory notes
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Delegate to the editors aspects raised by the following contributions: JCTVC-P0052/JCT3V-G0044, JCTVC-P0078/JCT3V-G0091 #8, JCTVC-P0155/JCT3V-G0144, JCTVC-P0181/JCT3V-G0159, JCTVC-P0130/JCT3V-G0131.
During the plenary of JCT-3V Fri PM, it was asked whether any HLS related document submitted as input to JCT-3V would not have found proper attention and disposition in the joint BoG. No such complaints were made.
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